The present disclosure relates to an electrophotographic image forming apparatus for forming an image by using toner.
In an image forming apparatus, generally, an electrostatic latent image formed on an image carrier such as a photoconductor drum is visualized with toner in the developing device, and the toner image is transferred to a recording medium. At this time, some toner may not be transferred to the recording medium and remain on the surface of the image carrier. As a result, the residual toner is removed from the surface of the image carrier by a cleaning device.
The residual toner removed from the surface of the image carrier is collected, as waste toner, in a waste toner collection container. The waste toner may be conveyed in the following manner before it reaches the waste toner collection container.
The waste toner removed from the surface of the image carrier is conveyed to a predetermined position in the horizontal direction by a first screw. The predetermined position is connected with a waste toner pipe that extends downward, and when the waste toner reaches the predetermined position, the waste toner falls downward in the waste toner pipe. The lower end portion of the waste toner pipe is connected with a conveyance pipe which extends in the horizontal direction and in which a second screw is provided. The waste toner that has entered the conveyance pipe is conveyed in the conveyance pipe by the second screw, and is discharged to a waste toner collection container that is provided at a predetermined position of the conveyance pipe.
In the conveyance configuration as such, the waste toner may clog a connection part of the conveyance pipe and the waste toner pipe. The following may be one of the causes of the clogging.
Since the waste toner has low fluidity, the waste toner is likely to stick to an inner wall of the pipe. Once waste toner sticks to the inner wall, part of newly fallen waste toner sticks to the waste toner that has stuck to the inner wall. This goes on and on and results in a relatively large accumulation of waste toner. Such a large accumulation would clog the connection part.
In addition, there may be a case where the waste toner that is present in the conveyance pipe becomes bulky. In that case, the waste toner that has fallen in the waste toner pipe may accumulate on the waste toner that is present in the conveyance pipe, and the accumulation of the waste toner may reach the inside of the waste toner pipe and the waste toner may stick to the inner wall of the waste toner pipe. This allows accumulation of waste toner to be generated in the connection part of the conveyance pipe and the waste toner pipe. The accumulation causes a clog in the connection part.
If the pipe diameter of the conveyance pipe is made larger, the waste toner present in the conveyance pipe will become less bulky, and the waste toner in the conveyance pipe will not or rarely reach the inside of the waste toner pipe. In that way, the generation of the accumulation at the connection part will be prevented, and the clog of the waste toner will be prevented or restricted. However, in view of the demand for the miniaturization of the image forming apparatus in recent years, the method is not preferable since the apparatus will be larger in size if the pipe diameter is made larger, which is against the demand for the miniturization.
There is known a configuration for solving the above-described problem in which a screw is provided in the waste toner pipe such that the screw scrapes off the waste toner that has stuck to the inner wall of the waste toner pipe.